Recently, for environmental protection, development of new energy alternative to fossil fuel such as petroleum oil or the like and technical development for efficiently utilizing energy have become promoted. As part of these, solar power generation and wind power generation are being rapidly popularized. However, these power generation methods utilizing natural energy are susceptible to the weather, and, therefore, the output power is often unstable. Accordingly, in massive introduction of such new energy, electrical storage technology for leveling output power and also electrical storage technology for effectively utilizing the electric power to be generated in light-load time such as nighttime or the like are indispensable. As a relatively large-scale storage battery for use for storage of such new energy, there are mentioned a sodium sulfur battery (NAS battery), a redox flow battery, a lead storage battery, etc., and these have been tried in verification test researches.
On the other hand, as storage batteries for mobile electronic appliances such as typically mobile phones and notebook-size personal computers, a lithium ion secondary battery has become widely popularized. As relatively large-sized storage batteries on a level usable as driving power sources for hybrid vehicles or electric vehicles, at present, a nickel hydrogen secondary battery is the mainstream. In future, however, for meeting the needs of high-performance storage batteries, lithium ion secondary batteries are expected to be further popularized also for driving power sources for vehicles. Further in future, application of lithium ion secondary batteries would be taken into consideration also for storage of new energy. In view of these, recently, high-capacity lithium ion secondary batteries have become strongly desired.